1. Field of the Invention
The present invention relates to a functional chip to be used while stacked on another chip and a stack structure formed by such stacked functional chips, the chips and the stack structure thereof being directed to achieving high mounting density. In particular, the present invention relates to a very large scale integrated (VLSI) circuit fabricated by stacking a plurality of semiconductor chips on each other.
2. Description of the Related Art
In the conventional practice in which semiconductor chips are packaged one by one, since the packaged semiconductor chips inevitably have increased volumes, it is difficult to improve mounting density. In order to improve mounting density, a plurality of substrates on which the semiconductor chips are mounted may be stacked on each other to form a multi-layer structure. However, this method requires sophisticated and complicated stacking techniques.
Thus, stacking a plurality of functional chips, such as semiconductor chips, which must be integrated by an integration technique, has required complicated stacking techniques and has not been capable of readily achieving high mounting density.